Transfer device for metal plates

ABSTRACT

A transfer device for shifting metal plates laterally from a rollway to a stacking box includes a displaceable transfer table by which the plates are lifted off the rollway and conveyed towards the stacking box, and on which the plates travel into engagement with a stop in the stacking box. The transfer table is provided with means which cause the plates to drop gently into the box when the transfer table is moved back again. Means are disclosed for controlling the height of the drop in relation to the prevailing height of the stack in the box.

United States Patent Neumann et al.

[ Aug. 29, 1972 TRANSFER DEVICE FOR METAL PLATES Inventors: Karl Josef Neumann; Otto 0stbringhaus, both of St. lngbert-Saar,

Germany Moeller & Neumann GmbH, Ensheimer, Germany Filed: Dec. 28, 1970 Appl. No.: 101,801

Assignee:

Foreign Application Priority Data Dec. 22, 1969 Germany ..P 19 65 113.9

US. Cl. ..271/63, 214/6 DK, 271/71 Int. Cl. ..B65h 29/50 Field of Search ..271/71, 68, 63; 214/6 DK References Cited UNITED STATES PATENTS Dryon ..214/6 DK ll/l968 3,429,469 2/ 1969 Peterson ..214/6 DK X 3,154,201 10/1964 Busch ..271/71 X 2,406,489 8/1946 Case ..271/DlG. 3 3,395,916 8/1968 Dobson et al ..271/88 Primary Examiner-Evon C. Blunk Assistant ExaminerBruce H. Stoner, Jr. Att0rneyJohn J. Dennemeyer [5 7] ABSTRACT A transfer device for shifting metal plates laterally from a rollway to a stacking box includes a displaceable transfer table by which the plates are lifted off the rollway and conveyed towards the stacking box, and on which the plates travel into engagement with a stop in the stacking box. The transfer table is provided with means which cause the plates to drop gently into the box when the transfer table is moved back again. Means are disclosed for controlling the height of the drop in relation to the prevailing height of the stack in the box.

5 Claims, 3 Drawing Figures TRANSFER DEVICE ron METAL PLATES The invention relates to a transfer device for metal plates by which plates are shifted laterally from a rollway to a stacking box, the device comprising a transfer table which is guided in guide rails which can be pivoted up and down, and which has carrier arms which extend between the rolls of the rollway and which are provided with idler rolls over which the plates run off, when the transfer table is in a downwardly inclined position, against a stop of the stacking box, the plates being released for a free drop by the return movement of the transfer table.

A transfer device of this kind operates in the manner that the transfer table is lowered in the region of the rollway below the rollway plane when a plate to be removed runs in. After the rollway has been stopped, the running rails which are pivotally mounted outside the rollway, and with them also the returned transfer table, are rotated upwardly whereby the metal plate is received by the transfer table. The plate rests then on the idle rolls of the carrier arms constituting the transfer table and is displaced by stops or by upwardly displaceable drive dogs, when the transfer table is moved forward by a cable drive or the like into a position over the stacking box. Thereafter the guide rails and thus also the transfer table are pivoted into a downwardly inclined position, and the plate runs on the idler rolls, against the stops of the stacking box. The transfer table is subsequently driven back while still under the plate which remains against the stop whereby this plate is tilted downwardly and drops into the stacking box. In this manner a plate stack is formed.

Since the carrier arms of the transfer table must have a considerable height for reasons of rigidity, the height which the plates are allowed to drop is considerable in the known transfer devices of the kind described.

The production of noise and dust connected with a great dropping height of the plates is often considered to be a disadvantage.

I It was found that a great dropping height per se is less responsible for the production of noise and dust than the fact that the rear edge of a tilting plate is suddenly released during the return movement of the transfer table. In order to slow the sudden release and thus to counteract the production of noise and dust, the invention proposes that the free stack-facing ends of the carrier arms of the transfer table are provided with downwardly inclined slide faces on which the rear edge of the metal plates slides down when the transfer table is moved back. The inclined slide faces may be formed on the carrier arms of the transfer table, or they may alternatively be attached to the carrier arms in the form of continuous curved plates. in order to avoid any score marks at the rear edges of the metal plates it is advisable to coat the inclined slide faces in a wear resistant scratch-reducing manner, e.g. with a layer of Teflon (Registered Trade Mark) deposited thereon. The trade name Teflon" is used here in lieu of all fluoro-carbon resins which have the same effect and which are characterized by particular wear and scratch resistance.

As a further measure for reducing the dropping height of the plates the carrier arms of the transfer table are preferably arranged to be pivoted down as closely as possible to the respective uppermost plate of a stack. For this purpose it is known to dispose at the stack-facing end of the carrier arms a control device for limiting the downward pivotal movement of the carrier arms to a defined spacing from the respective uppermost plate. According to the prior art such a device consists of running rollers which are disposed on the underside of the carrier arms and which are arranged to be placed on the uppermost plate, (German Gbm No. 6,750,718).

Apart from the fact that the impact of the running rollers on the plate may leave score marks behind, which can be avoided only by reducing the speed of the downward pivotal movement to an output reducing extent, it must be considered as a disadvantage in the apparatus known heretofore that the transfer table is supported on the uppermost plate exclusively by the running rollers and thus can drop suddenly when, during the stacking of plates of different widths, the running rollers leave a stack of plates having a'reduced width. Although the running rollers may be retained in the subject of the present invention for reasons of safety, the invention proposes for fixing a selected inclination of the carrier arms that the device for limiting the downward pivotal movement of the carrier arms comprises an electrical sensing device which detects the level of the respective uppermost plate of a stack and determines the spacing of the carrier arms from this plate and which, when the spacing falls below a nominal value, releases a control signal for stopping the downward pivotal movement of the carrier arms.

In one possible construction the absolute height of the plate stack is determined by photoelectric means and a signal obtained thereby is compared with a signal which depends upon the pivotal position of the carrier arms, in order to detect the actual spacing of the carrier arms from the respective uppermost plate, the control signal referred to above being released when the actual spacing attains the desired nominal spacing.

However, alternatively, apparatus may be used which reacts directly on a magnetic basis to spacing changes, e.g. sensors or for a simple on/off control magnetic proximity switches, so-called captors, which are disposed at the free stack-facing end of the carrier arms. These proximity switches are inexpensive compared with the steplessly operating sensor controls and are entirely satisfactory for the present purpose.

It appears sufiicient when the magnetic proximity switch or switches is or are switched on by limit switches when the transfer table is moved towards the stacking box, and are functionally disconnected after they have responded and stopped the downward pivotal movement of the carrier arms and the guide rails. The transfer table is then moved back while it is still in the inclined position determined by the guide rails even if the proximity switches upon leaving a stack of narrow plates register suddenly a large spacing between the carrier arms and the uppermost plate of a stack of wider plates located therebelow.

Alternatively the arrangement may be made so that the proximity switch or switches remain in function during the return movement of the transfer table and permit further downward pivotal movement of the carrier arms when the spacing thereof from the respective uppermost plate of a stack has increased beyond the nominal spacing. This arrangement has an advantageous effect when, during stacking of the first plates, the guide rails and thus the transfer table assume a relatively steep inclination towards the bottom of the stacking box. If the transfer table were than moved back without change of the inclination, the spacing of the slide faces of the carrier arms would increase relatively to the bottom of the stacking box. The drop height existing when the rear edge of the plates to be stacked slides down is maintained at a minimum in that the proximity switches remain in function, responding under certain circumstances in a step-like manner, and permit further downward pivotal movement of the carrier arms for short periods.

One constructional example of a plate transfer device according to the invention is described below with reference to the accompanying drawings, in which:

FIG. 1 illustrates a side view considered in the direction of the rollway of an outer carrier arm of a transfer table and its guide rail the transfer table being pivoted in a downwardly inclined position,

FIG. 2 illustrates a circuit arrangement for controlling a hydraulic lowering drive for the guide rails, and

FIG. 3 illustrates a photoelectric control for a circuit arrangement according to FIG. 2.

Between rolls 1 of a rollway and distributed over a length of the latter corresponding to the maximum plate length to be manipulated, there are located guide rails 2 which can be pivoted up and down around a bearing 3 mounted outside the rollway. Carrier arms 4 which in their totality form a transfer table 5 are displaceable in the guide rails 2. In the illustrated downwardly inclined position of the transfer table 5, the rollers 6 of the carrier arms are disposed in the extreme forward position. In the returned position of the transfer table, in which the latter is located in the region of the rollway, the rollers 6 assume the position 6' illustrated by broken lines;

The carrier arms 4 are provided with idler rolls 7. Furthermore the carrier arms are provided with a rearward stop 8 as well as with drive dogs 9 and 10 which yield resiliently in a known manner when a plate lies thereon. The drive dogs 10 which are shown in operation in the present constructional example engage behind a plate 12 of small width.

For displacingthe transfer table 5 there serves a cable drive 14 with two guide rollers l5, l6 and a driven roller 17.

A lifting and lowering drive for the carrier arms 2 consists of at least two hydraulic cylinder-piston devices including cylinders 18 which are supported by a bearing 19 in an oscillating manner, and piston rods 20 which guided by guides 21 engage at a bearing 22 a support beam 23 on which all guide rails 2 rest.

In accordance with the invention, the carrier arms 4 are constructed at their free stack-facing ends in the form of slide faces 4a which are downwardly inclined in an arc-shaped manner. In operation the narrow plate 12 supported by three idler rolls 7 impinges because of its inertia and the prevailing inclination of the transfer table 5 against a stop 24 of a stacking box 26; subsequently the transfer table 5 is moved back by actuation of the cable drive 14 to 17, and the plate 12 is caused to tilt down forwardly and its rear edge to slide down on the slide face 4a, the plate being deposited smoothly on an uppermost stack 28 of narrow plates.

During the release of the plate 12 the latter drops in free fall at most through a distance equal to the spacing of the lower edges 4b of the carrier arms 4 from the top of the stack 28. Therefore, the aim must be that the spacing of these lower edges 4b from the respective uppermost plate of the stack is a minimum. An adjustment of such defined spacing is to be controlled in accordance with an optical feature of the invention by magnetic proximity switches, so-called captors, which are disposed at the free end of at least one of the carrier arms 4 and which deliver an electrical signal for detaining the pistons in the hydraulic cylinders 18 which serve for adjusting the pivotal movement of the guide rails 2.

FIG. 2 illustrates a control diagram for the actuation of a cylinder-piston device 18, 20 under the effect of control signals from a magnetic proximity switch 30. It may be assumed that the cylinder 18 contains a piston, the piston rod 20 of which moved down, when a fluid return pipe is open, owing to the inherent weight of the transfer device. Therefore, the cylinder 18 requires only a control pipe 32 which can be selectively connected by means of a switch 36 through a spring loaded two-way valve 34 to a pressure pipe 38 or to a return pipe 40. A fluid pump 42 takes pressure fluid, e.g. oil, from a container 44. The pressure pipe 38 is protected against overpressure by a by-pass valve 46.

The return pipe 40 does not lead directly to the container 44 but passes through a magnetic valve 48. A solenoid 49 of this valve 48 is arranged to be energized by two auxiliary control circuits 50 and 52 connected in parallel with each other. The control circuit 50 is normally open owing to a switch 31 which can be actuated by a magnetic proximity switch 30; similarly the control circuit 42 is normally open owing to a switch 55 which can be actuated by a push button 54. Normally the valve 48 is set for throughfiow.

The manner of working of the circuit according to FIG. 2 is as follows:

When the switch 36 is open, the two-way valve is in the position in which the pressure pipe 38 is connected to the control pipe 32 and the piston rod 20 moves upwardly, so that the transfer table 5 can receive a plate from the rollway with the roll 1. In the highest pivotal position 5 of the transfer table 5, the switch 36 is closed manually or by a sequence control whereby the two-way valve 34 moves into the illustrated position in which the control pipe 32 is connected to the return pipe 40. Since the valve 48 is normally set to throughflow the piston rod 20 moves down whereby the transfer table 5 together with the guide rails 2 is pivoted downwardly. During this movement the mag netic proximity switch 30 approaches the uppermost plate of the stack 28 whereby its magnet current rises and delivers a control signal at a certain spacing from the uppermost plate which signal closes the switch 31 in the auxiliary control circuit 50 (FIG. 2). Thereby the position of the magnetic valve 48 is changed so that the return pipe 40 is shut off and the downward pivotal movement of the guide rails 2 is stopped. Taking into account the response times of the proximity switch 30 and of the fluid control valves, the lower edge 4b of the carrier arms 4 of the transfer table 5 is then to assume as small as possible a spacing from the respective uppermost plate of a stack. For reasons of safety the free ends of the carrier arms 4 are additionally provided with running rollers 56 which come into engagement with the uppermost plate if accidentally the downward pivotal movement of the guide rails 2 fails to be limited by the control according to FIG. 2.

However, the position of the piston in the lifting and lowering cylinder or cylinders 18 may alternatively be manually secured by manually closing the switch 55 by means of the push button 54. In this case the auxiliary control circuit 52 is closed in order to change the setting of the valve 48 and to shut off the return pipe 40.

When the switch 31, in response to a control signal of the magnetic proximity 30, has been closed, it may have been arranged to remain closed until the transfer table 5 has been returned and the plate 12 released. In this case the transfer table moves back parallel to the inclined plane which is determined by the guide rails 2. However, if one considers the situation existing when a first plate of maximum width is stacked as is indicated for the lowermost stack 29, it will be seen that in the steep downward inclination to which the transfer table 5 is adjusted, as shown for the position 5" illustrated by broken lines, the slide faces 4a which control the release of the plate for the free fall are progressively removed from the bottom of the stacking box 26 as the transfer table 5 is moved back. It is therefore advisable to leave the magnetic proximity switch or switches 30 in the function during the return movement of the transfer table 5 so that the switch 31 opens again when a defined spacing of the proximity switch 30 from the bottom of the stacking box 26 is exceeded, and the downward pivotal movement of the guide rails 2 is continued until the switch 31 is closed again by a new control signal and the return pipe 40 is shut off again. The same process of repeatedly closing. and opening the switch 31 occurs also when a proximity switch 30 which is continuously operative travels over the steps formed by the differently wide stacks 28, 27 and 29.

The invention obviously includes in place of the inexpensive magnetic proximity switches, use of other sensing devices operating without contacting, e.g. sensors; however, these require an increased electrical expenditure buy permit a stepless adjustment of a desired nominal spacing between the lower edge 4b of the carrier arms 4 and the respective uppermost plate to be obtained within narrow limits.

A solution of the problem of providing automatic adjustment of the transfer table to a small plate spacing by photoelectric means may consist in that according to FIG. 3 a light-sensitive device 60, e.g. a photo cell, is disposed below a central running rail 2 and is arranged to be energized by a light source 61 which is disposed beyond the stacking box 26 and which emits a substantially horizontal beam of light rays 62 extending perpendicularly from the source 61. The beam of light considered from the light-sensitive device 60 is progressively covered in the lower region by the growing plate stack 28, 27 and in the upper region by a plate constituting the slide surface 4a. A flexible apron or shield 63 of rubber or the like is suspended from the underside of the carrier arms 4, and when the transfer table 5 i ts down, th hield rted th permosl p l te and cove l's then alsz llfie rays g Za \shl li are illustrated in FIG. 3 as not yet intercepted. Owing to the fact that thereby the light-sensitive device 60,

e.g. the photo cell, does no longer deliver a photo-electric current the switch 31 (FIG. 2) is closed and the downward pivotal movement of the running rails 2 is stopped.

The progressive reduction of the quantity of the light falling onto the light-sensitive device may be utilized for smoothly initiating the stoppage of the pivotal downward movement by the use of controllable restrictor valves.

What we claim is:

l. A device for transferring metal plates laterally from a rollway to form a stack of plates in a stacking box comprising:

a. a transfer table;

b. guide rails pivotable between a first position for receiving plates from the rollway and a second position for discharging plates into the stacking box, said transfer table being displaceably guided on said guide rails;

0. means for controlling the pivotal movement of said guide rails;

. said control means including sensing means having a light source and a light-sensitive device, at least one of said sensing means being separate from said guide rails and fixed in a stationary position with respect to the movement of said guide rails, and at least one of said sensing means being elongated approximately in the direction of stacking height increase whereby an increase in stacking height progressively reduces the quantity of light passing between said light source and said light-sensitive device to smoothly effect stoppage of the pivotal movement of said guide rails.

2. A device as defined in claim 1, wherein at least said light source is separate from said guide rails and fixed in a stationary position with respect to the movement of said guide rails.

3. A device as defined in claim 1, wherein at least said light source is elongated in the direction of stacking height increase.

4. A device as defined in claim 1, wherein at least said light source is separate from said guide rails and fixed in a stationary position with respect to the movement of said guide rails, and is elongated in the direction of stacking height increase.

5. A transfer device according to claim 1 including a plate-like cover at one end of said transfer table and a flexible shield attached to said transfer table and adapted to come into engagement with the uppermost portion of the stack, said cover and said shield being effective to progressively reduce the quantity of light passing between said light source and said light-sensitive device. 

1. A device for transferring metal plates laterally from a rollway to form a stack of plates in a stacking box comprising: a. a transfer table; b. guide rails pivotable between a first position for receiving plates from the rollway and a second position for discharging plates into the stacking box, said transfer table being displaceably guided on said guide rails; c. means for controlling the pivotal movement of said guide rails; d. said control means including sensing means having a light source and a light-sensitive device, at least one of said sensing means being separate from said guide rails and fixed in a stationary position with respect to the movement of said guide rails, and at least one of said sensing means being elongated approximately in the direction of stacking height increase whereby an increase in stacking height progressively reduces the quantity of light passing between said light source and said light-sensitive device to smoothly effect stoppage of the pivotal movement of said guide rails.
 2. A device as defined in claim 1, wherein at least said light source is separate from saiD guide rails and fixed in a stationary position with respect to the movement of said guide rails.
 3. A device as defined in claim 1, wherein at least said light source is elongated in the direction of stacking height increase.
 4. A device as defined in claim 1, wherein at least said light source is separate from said guide rails and fixed in a stationary position with respect to the movement of said guide rails, and is elongated in the direction of stacking height increase.
 5. A transfer device according to claim 1 including a plate-like cover at one end of said transfer table and a flexible shield attached to said transfer table and adapted to come into engagement with the uppermost portion of the stack, said cover and said shield being effective to progressively reduce the quantity of light passing between said light source and said light-sensitive device. 